smith



Jan. 24, 1956 A. D. SMITH 2,732,083

ARTICLE HANDLER Filed Sept. 18, 1951 4 Sheets-Sheet 1 I INVENTOR./}5RTHUR Din/v SMITH ATTORNEY Jan. 24, 1956 A. D. SMITH ARTICLE HANDLER4 Sheets-Sheet 2 Filed Sept. 18, 1951 INVENTOR. ERTEH R EfiN MITH By Q 5W NGHK T Wm ATTORNEY Jan. 24, 1956 A. D. SMITH ARTICLE HANDLER 4Sheets-Sheet 3 Filed Sept. 18 1951 H An w W w mm W QW D AC m R U m. RyA, 0% B N mN\ .w w wmiam Jan. 24, 1956 A. D. SMITH ,0

ARTICLE HANDLER Filed .Sept'. 18. 1951 '4 Sheets-Sheet 4 INVENTOR. is 'ru 1:32am SMITH BY 7 6 OTR/ ATTORNEY United States Patent ARTICLE HANDLERArthur Dean Smith, Spokane, Wash, assignor to Kaiser Aluminum & ChemicalCorporation, Oakland, Calif, a corporation of Delaware ApplicationSeptember 18, 1951 Serial No. 247,143 5 Claims. (Cl. 214-1) Thisinvention relates to hoisting and lifting tongs for picking up andtransporting heavy articles from one location to another. Moreparticularly, it is concerned with providing novel hoisting clamps ortongs for grasping and transporting coiled metal stock from one place toanother.

The hoisting clamps or tongs, which have been employed in the past forgraspng and transporting coiled metal stock from one place to another inrolling mills and the like, have not proven entirely satisfactory forone or more reasons.

These clamps or tongs'we're ordinarily suspended from a crane affixed toa trolley which travels along an overhead track in a rolling mill orfactory. These clamps or article engaging tongs were usually of a toggletype and operated more or less on the same principle as ice tongs. Thus,when one of the tongs was brought into engagement with the outer surfaceof the coil and the other of the tongs brought into contact with theinner surface of the coil which was usually located in an upendedposition and a lifting force was applied to the tongs, they were forcedtogether so as to grasp the coil of metal between them whilesimultaneously lifting the coil of metal to a predetermined height,after which it was carried by the crane and tongs to another location.

However, with these toggle type of clamping tongs, it was never possibleto obtain a true, firm and solid grip on a coil of metal. While in thisloose grip of the tongs, the several wraps of metal in the coil adjacentto the tongs were frequently pulled out of place, thereby scratching orscoring the surface of the metal and rendering that portion of the coilwhich had been scratched useless for 'certainpurposes.

This problem was particularly significant when these clamping tongs wereused for transporting coils of aluminum in a rollng mill or factory,since the appearance of the aluminum is very important in the laterfabricationof many aluminum products from such coiled stock.Accordingly, those portions of the aluminum coil which were scratched orscored during transport by the tongs ordinarily had to be relegated tothe scrap heap. The amount 'of waste over a period of time through theuse of such toggle type of tongs in hoisting and transporting metalcoils, and particularly coils of aluminum, is 'ob- VlOllS.

It has been found, however, that by utilizing a novel clamping tongapparatus which will securely engage the coiled stock and not allow anyslippage of the coil between the "clamping tongs that scoring orscratching of the metal coil during transport can be preventedeffectively. In addition, this novel hoisting apparatus is soconstructed that the clamping tongs cannot be elevated until theclamping tongs have vcompletely and securely clamped or gripped one ormore coils. These clamping ton-gs are also so constructed that once theclamping tongs have been raised to a predetermined height, preferably bymeans ofa suitablehydraulic-hoisting cylinder, the weight of the coiland the tongs will cause a back pressure in the hoisting cylinder whichin turn is transferred to a second hydraulic cylinder used to operatethe clamping tongs themselves, thereby keeping the jaws clamped. Inother words, the clamping jaws cannot be unclamped as long as there is aweight hanging on or suspended from the tongs.

These and other objects are accomplished by providing a hoistingapparatus comprised of a hoisting frame with a pair of clamping tongsdependingly attached thereto. One of the tongs is removably attached tothe frame member at a fixed point thereon and the other of said tongs isarranged for reciprocatory movement toward and away from the first tongafter the first tong has been removably attached to the frame ata'predetermined point thereon. Guide means are also provided for thereciprocating tong and a hydraulic cylinder and cooperating piston arepreferably used for actuating the reciprocating tong.

A vertically disposed hydraulic cylinder and cooperating piston areattached to the hoisting frame member and these are adapted to lift andlower the frame. Common conduit means are utilized for supplying fluidto both of the aforesaid hydraulic cylinders. A fluid pressure operatedvalve is located in the conduit means and this valve operates to controlthe passage of fluid first to the cylinder adapted to actuate thereciprocating tong and then to the cylinder adapted to lift the hoistingframe. A second valve is also located in the conduit means and thissecond valve causes fluid to flow away from the hoisting cylinderthrough the conduit means and toward the reciprocating tong actuatingcylinder, after the hoisting cylinder has been operated to lift thehoisting frame and the tongs attached thereto to a predetermined height.

Accordingly, it is an object of this invention to provide a novelhoisting device having article engaging and clamping tongs which areadapted to securely engage an article therebetween.

A further object of this invention is to provide a novel hoisting devicehaving article engaging and clamping tongs which cannot be unclamped aslong as an article is held in suspension by the clamping tongs. vAnother object of this invention is to provide a novel hoisting devicehaving article engaging and clamping tongs 'which cannot be elevateduntil the clamping tongs have first firmly gripped the article to behoisted.

A further object of this invention is to provide a novel hoistingdevice'having article engaging and clamping tongs which can be adjustedso as to engage coils of metal stock of various sizes and/ or aplurality of coils at one and the same time.

Other objects and advantages of the instant invention Will become moreapparent from a consideration of the following detailed description whentaken in conjunction with the following drawingswherein:

Figure 1 is'a side elevational view partially broken of the hoistingapparatus of the instant invention;

Figure 2 is a plan view of the main frame of the hoisting apparatus whentaken along lines 22 of Figure 1;

Figure 3 is a sectional view of the main frame of the hoisting apparatusand the clamping tongs carried thereby when taken along lines 3-3 ofFigure 2 with the clamping tongs properly adjusted and the main frameproperly balanced so that the apparatus can be .used to lift two coilsof metal;

Figure 3a is a sectional view of the main frame of the hoistingapparatus and clamping tongs carried thereby with the clamping tongsadjusted and the frame properly balanced so as to'carr-y one coil;

Figure 4 is a cross-sectional view of the main frame and the clampingtongs carried thereby when taken along lines 4--4 of Figure 2; and

Figure is a schematic drawing of a suitable hydraulic system employed inthe operation of the hoisting apparatus of the instant invention.

With further reference to the drawings and particularly Figures 1, 2 and3, the hoisting apparatus is generally comprised of a main framemember 1. This frame member 1 in turn is roughly comprised of a pair ofoppositely disposed, parallel and elongated plates 2 and 2.

These plates are joined together by means of a suitable bridging member3 which may be welded or otherwise secured to the anchoring plates 4,which are in turn bolted to the inside surfaces of plates 2 and 2'.Bridging member and plates 4 can also be formed from a single piece ofmetal as indicated in Figure 2. The plates 2 and 2 are also securedtogether by means of the pivot pin 6 to which the clevis 5 is alsoattached.

The upper part of the clevis 5 is provided with a hollowed-out threadedportion 7 which is adapted to receive the externally threaded studelement 8 attached to the lower end of a piston rod 9 which is adaptedto reciprocate in the hydraulic hosting cylinder 10, hydraulic cylinder10 in turn being dependingly attached ot a travelling overhead trolley11 by means of a suitable ball swivel mounting 12.

This trolley 11 is mounted on wheels 11' which engage the overheadtracks 9' and trolley 11 and may be driven by any suitable power meansalong these tracks 9. However, since this trolley does not form any partof the invention, it has neither been shown or described in detail.

The trolley 11 also has mounted thereon a vane type hydraulic pump 13driven by a suitable motor 14. A fluid storage tank 15 is also locatedupon the trolley and the function and operation of pump 13, motor 14,and tank 15 will be hereinafter more fully described.

The clamping tongs or jaws 17 and 18, which are carried by the mainframe 1, are each cast from a separate piece of metal. Clamping tong 17is so cast from a piece of metal as to be provided with a flat bodyportion 19. Body portion 19 has an elongated aperture or slot 20 locatedtherein. One end of the body portion 19 terminates in a downwardlyprojecting arm 21, having an annular recessed portion 22 located in theinner marginal edge thereof.

An article gripping plate 24 is attached to arm 21 by means of aprojecting lug or knob 23 formed integrally therewith, which lug isadapted to become lodged or seated within the recessed portion 22. Thisknob 23 can be secured to arm 21 by means of the anchoring plate 23 whenthis plate is bolted to one side of the arm 21 and one end of the plate23 is inserted in a slot 24' in the knob 23. The outer surface of plate24 is advantageously convex so as to be able to correctly engage theinner hollow center portion of a coil of metal, such as aluminum.

The other extremity of clamping tong 17 terminates in an upwardlyprojecting standard 25. Rigidly attached to the intermediate section ofstandard 25 by means of the nut 26 is the threaded extremity 27 of apiston rod 28, which is adapted to reciprocate in a hydraulic cylinder29, threaded portion 27 being insertable through the hole 27 in standard25.

This hydraulic cylinder 29 in turn is mounted upon and rigidly securedto the upper surface of the flat body portion 30 of the other clampingtong 18. This latter clamping tong is also cast from a single piece ofmetal in such a manner that in addition to being provided with a bodyportion 30, clamping tong 18 is also provided with a depending arm 31.

Arm 31 is also provided with a recessed portion 32, within which aprojecting lug 33 on the article grasping plate 34 is adapted to beanchored in the same manner as plate 24 is aflixed to arm 21 on tong 17.

The other extremity of tong 18 is provided with an which abuts one endof the cylinder 29. A pair of side members 39 are formed integrally withbackstop 36 and they are also provided with openings 40 through which asuitable bolt 41 may be inserted so as to rigidly anchor side members 39and tong 18 to the plates 2 and 2' when this bolt has also been insertedin one of the twin openings 38 and 38 in each side plate.

It will be observed by referring to Figures 2, 3, 3a and 4 that each ofthe side plates 2 and 2 is so made as to be provided with achannel-shaped slot or keyway 44 in the bottom portion thereof, thesechannels being defined by the projecting and spaced rib portions 45 onthe respective side plates. The body portion 19 of tong 17 and the bodyportion 30 of tong 18 are insertable in the several slots or keyways 44of the side plates. They are placed one upon the other in such a waythat arm 31 of tong 18 projects through the slot 20in tong 17, it beingunderstood, of course, that plate 34 is attached to tong arm 31 onlyafter the latter has first been inserted through slot 20 in tong 17.

From the above description it will be understood that once tong 13 isrigidly fixed or attached to the main frame, tong 17 is made movablewith respect thereto by means of the piston 28 which is adapted toreciprocate in the cylinder 29 rigidly affixed to tong 18.

It will also be observed that the instant apparatus is adapted to liftand transport either one or two coils simultaneously. When it isemployed to transport but one coil 100, tong 18 as indicated in Figure3a is moved along slot 44 until it is located slightly to one side ofthe clevis 5 and pin 6, after which it is anchored rigidly to the frame1 by means of the bolt 41 when this bolt is inserted in the hole 38 ineach of the side plates 2 and 2 and through the openings 40 in the sidemembers 39 of the tong 18.

In order to balance the frame when the tong 18 is moved to the positionindicated in Figure 3a, a counterbalancing weight 50 is then placedbetween plates 2 and 2 at the other end of the main frame 1, weight 50being secured to the side plates by means of the pins 51. At this timealso pin 6 for the clevis 5 is inserted in the opening 37 in the sideplates.

Whenever the device is employed to lift two coils and 100',.tong 18 isshifted in the opposite direction along keyway 44 until it reaches theposition shown in Figure 3, at which time weight 50 is removed and pin 6for clevis 5 is then removed from the openings 37 in the side plates 2and 2 and inserted in the openings 37 of the said side plates.

When the device is employed to hoist two coils, a suit able pinion gear53 is located above cylinder 29 attached to tong 18, pinion gear 53being held in the proper position by means of the upper and lowerbridging members 54 and 54', which are suitably attached to side plates2 and 2 by means of the screws 55. Web members 54 and 54' both havealigned openings therein in which the shaft 53 of the gear 53 isinserted.

This pinion gear is adapted to mesh simultaneously with a rack 56attached to the cylinder 29 and a second rack 57 rigidly affixed tostandard 25 which forms part of tong 17. The purpose of racks 56 and 57and pinion gear 53 is to center the tongs 17 and 18 and to keep themlevel, as well as to aid in properly balancing the hoisting device as awhole during its suspension from hoisting cylinder and piston 9 and 10,during the time the tongs are used to grasp and transport two coils ofmetal.

Suitable spacers 60 and 61 for the tongs may be In serted between and beremovably attached to the side plates 2 and 2' at each of their ends,spacer 61 being removed when the device is used to hoist but one coil.

When one coil is grasped by the tongs 17 and 18, one of the tongs isadapted to engage the inside of the coil while the other engages theoutside of the coil so that the-coil may be firmly and securely clampedtherebetween.

upstanding backstop 36 lNhen two coils are engaged each of the tongsengage the nside surface of a separate coil as indicated in Figure 3.

The arrangement and operation of the hydraulic circuit. for operatingthe hoisting cylinder and piston 9 and 10 and clamping tong cylinder andpiston 29 and 28 will now be described.

By referring to Figure 5 it will be observed that the hydraulic systemincludes a motor driven hydraulic pump 13, which pumps fluid out of tankthrough line 312) to the entry port 71 of a solenoid-operated 4-wayvalve One of the discharge ports of valve 72, namely port 73, isconnected to tank 15 by means of the conduits or lines 75 and 75, line75 connecting the main exhaust port 74 of valve 72 directly to the tank15. Another discharge port 77 of valve 72 is connected by means ofconduits 78 and 79 to a second solenoid-operated 4-way valve 80. Line 78also connects with a sequence and pressure-operated valve 81.

The discharge ports 83 and 82 of the second valve 80 are connected tothe rod end and head end of the tong actuating cylinder 29 by means ofthe conduits 84 and 85 respectively. Valves 72 and 80 are advantageouslyelectrically operated. Thus, when the tongs 17 and 18 are in anunclamped position and are at rest about a coil to be hoisted, thepushing of a clamp button 86 of a suitable electric switch 80, alsoshown diagrammatically n gure wi l aus the ners za g of valve 72 inSllch a manner that port 71 thereof will be connected with dischargeport 77, thereby allowing fluid to pass through conduits 78 and 79 tovalves 80 and 81. At this time also port 73 of valve 72 becomesconnected to port 74. Valve 81 remains closed by a suitable springmechanism until such time as pressure builds up in line '78 to thespring setting in valve 81. Initially, therefore, fluid is blocked fromentering the hoisting cylinder 10 through line 38 which connects valve81 with the hoisting cylinder. Instead fluid is first passed throughline 79 to inlet port 90 in the valve 80, which valve is also adapted tobe energized simultaneously with valve 72 by any suitable electricaldevice well known in the art when the clamp button 86 is pushed.

When in the clamp position discharge port 32. of valve 895 is connectedwith inlet port 90 and discharge port 83 of valve 80 is connected toexhaust port 1163 upon energization of valve 80. Fluid thus passes outof port 32 and through line 85 to the head end of the clamping cylinder29 through the opening 29 therein, and out of rod end of cylinder 29through line 84 to port 83 through valve 84} to port 110 through lines150 and 75 to tank 15, thereby actuating piston 28 and clamping tong orjaw 17 and drawing it closer to clamping tong or jaw 18 until both jawssecurely engage thecoil between them, at which time pressure builds upin lines 85 and 79 to a point where valve 81 opens, thus allowing fluidthen to flow through line 88 to the lower part of the hoisting cylinder10 which then operates to lift the clamping jaws and the article clampedthercbetween, such as a coil of aluminum.

Upon release of the clamp button 86 after the jaws or tongs have beenraised to the desired height, solenoidoperated valve 72 operates toblock the flow of fluid out of either cylinder 29 or 10, whilepermitting a free flow of fluid from the pump discharge line 70 backthrough the return line 75 since at this time when the valve isdeenergized or is in a neutral position the inlet port 71 of valve 72 isconnected directly to the exhaust port 74 of the valve 72, therebypermitting fluid to flow freely from the inlet port 71 to the exhaustport 74 and thus unload.- ing the pump. Valve 30, however, stillremainsenergized.

In the meantime, the gravity Weight of the jaws 17 and 18 and the coiland/or coils clamped therebetween causes a back pressure in the hoistingcylinder 10, and since the circuit remains open back pressure is alsocreated in 6 lines 88 and 79 and then through the inlet port 90 andoutlet port 82 of valve and through line 85. to the head end of theclamping cylinder 29, thereby creating a back pressure in this cylinderwhich acts to keep the tongs or jaws tightly clamped about the coil orcoils.

The jaws remain in this clamped position about the coil until the lowerpush button 95 of switch 80' is depressed. Depressing the lower pushbutton 95 causes valve 72 to be energized in such a manner thatdischarge port 77 becomes connected with exhaust port 74 while intakeport 71 becomes connected to discharge port 73.

Fluid is then allowed to discharge out or" the hoisting cylinder 10through valve 72 and back to the tank 15. Since port 71 is connected toport 73 and port 73 is connected to line 75 by means of auxiliary line75, the pump continues to by-pass under no load during the lowering ofthe tongs or jaws with their load.

Releasing of the lower push button 95 when the tongs have been loweredthe proper amount causes valve 72 to be actuated so that inlet port 71is again connected directly to the exhaust port 74. During all of thistime the position of valve 80 remains unchanged.

Thereafter the depressing of the unclamp push button 9.8 will causevalve 72 to be operated so that inlet port 71 becomes connected todischarge port 77, while discharge port 73 becomes connected to exhaustport '74. When push button 98 is pressed valve 80 is also simultaneouslyoperated so that inlet port 99 becomes connected to discharge port 83,while discharge port 82 becomes connected to exhaust port 110. Fluid isthereby evacuated out of line and through line 150 to return line 75 andthen back to the tank. Fluid in the meantime, of course, is also beingpumped from inlet port and out through discharge port 83 and line 85} tothe rod end of the cylinder 29 through port 28 so that the clamping jawsare forced apart and released from the coil. When the jaws 17 and 18reach their extreme open position, pressure builds up in lines 84 and 79to a point where valve 81 opens, thus allowing fluid to flow throughline 88 to the lower part of the hoisting cylinder 10 which thenoperates to lift the unclamped tongs away from the article just releasedand in position to be lowered onto the next article, such as a coil ofaluminum. It will be observed also that a suitable slot 175 may belocated in one of the side plates to provide suitable clearance for portelement 28' when the cylinder 29 is moved on the main frame as theapparatus is adjusted to pick up one coil or two coils. 9

Upon release of the unclamp button 98 after the jaws or tongs have beenraised to the desired height, solenoidoperated valve 72 operates toblock the flow of fluid out of either cylinder 29 or 19, whilepermitting a free fiow of fluid from the pump discharge line 70 backthrough the return line 75 since at this time when the valve isdeenergized or is in a neutral position the inlet port 71 of valve 72 isconnected directly to the exhaust port 74 of the valve 72, therebypermitting fluid to flow freely from the inlet port 71 to the exhaustport 74 and thus unloading the pump. Valve 80, however, still remainsenergized. The jaws remain in this unclamped position suspended aboveanother coil until lower push button of switch 89 is depressed.Depressing the lower push button 95 causes valve 72 to be energized insuch a manner that discharge port 77 becomes connected with exhaust port74 while intake port 71 becomes connected to discharge port 73.

Fluid is then allowed to discharge out of the hoisting cylinder 10through valve 72 and back to the tank 15. Since port 71 is connected toport 73 and port 73 is connected to tine 75 by means of auxiliary line75, the pump continues to by-pass under no load during the lowering ofthe tongs or jaws. This completes the cycle.

From the foregoing description it will be noted that valves 72 and 80are so constructed that depression of the clamp button 86 energizes thesame solenoid in valve 72 as is energized when the unclamp button 98 isdepressed, while depression of clamp button 86 shifts the solenoid valve8% in an opposite direction to that obtained when the unclamp button 98is pushed.

A pressure switch 91 is provided so that pushing of the wrong button on80' will not energize valve 84). For example, if the coil is suspendedin the tongs and the unclamp button 98 is pushed instead of the lowerbutton 95, valve 72 will shift but valve 80 will remain unchanged. Thisshifting of valve 72 will cause the tongs to raise to a higher positionas long as the button is held.

The hydraulic system may also be provided with suitable chcck valves 200and 201, a globe valve 202, and a relief valve 203, for protection ofthe system and to control the rate of flow in the system.

From the foregoing description it will also be observed that as long asthere is a weight han ing from the tongs or jaws, such as a coil, itcannot be released from the jaws. The safety feature of the apparatus istherefore obvious. If a slow leak develops in any of the valves orhydraulic cylinders, the only thing that can happen while the coil issuspendid in the air is that the coil will be slowly lowered to thefloor and then be released from the jaws. The only way in which a coilcould be dropped would be by breaking a hose to the clamping cylinder29. A hydraulic system is also preferably used to operate cylinders 10and 29. It will also be noted that the apparatus is simply constructedand can be easily repaired.

An advantageous embodiment of the invention has been herein described.It is obvious that various changes and modifications may be made thereinwithout departing from the spirit and scope thereof as defined by theappended claims.

I claim:

1. In a hoisting apparatus of the type described which is adapted tosecurely engage and then transport a coil of metal or the like from onelocation to another, the combination of a hoisting frame member, aplurality of clamping tongs carried by said frame member, one of saidclamping tongs being arranged for reciprocating movement toward and awayfrom another of said tongs, hydraulic cylinder and piston means foractuating said reciprocating tong, a second hydraulic cylinder andpiston means attached to the hoisting frame member for lifting andlowering the said frame member, pump means for supplying fluid underpressure to both of said cylinder and piston means, conduit meansconnecting said pump means to said first mentioned cylinder means,conduit means connecting said pump means to said second mentionedcylinder means, said second conduit means including a portion in commonwith said first mentioned conduit means, a fluid pressure operated valvelocated between the common portion of said first and second mentionedconduit means and said second mentioned cylinder and piston means forcausing fluid to be passed first to the cylinder means adapted toactuate said reciprocating tong and then to said cylinder means adaptedto lift said hoisting frame member, and valve means for cutting off theflow of fluid under pressure from said pump means to said common conduitmeans, whereby a back pressure will be exerted upon the piston of saidtong actuating piston and cylinder means due to the weight imposed uponsaid second mentioned piston and cylinder means.

2. A hoisting apparatus of the type described in claim 1, includingmeans for positioning one of the tongs at different points on the framemember, whereby the tongs may be adjusted so as to engage a plurality ofcoils.

3. In a hoisting apparatus of the type described which is adapted tosecurely engage and then transport a coil of. metal or the like from onelocation to another, the combination of a hoisting frame member, a pairof clamping tongs dependingly carried by the said frame member, one ofsaid tongs being removably attached to said frame member, and the otherof said tongs being arranged for reciprocatory movement toward and awayfrom said first tong after the first tong has been removably attached tosaid frame member at a predetermined point thereon, hydraulic cylinderand piston means for actuating said reciprocating tong, a secondhydraulic cylinder and piston means attached to the hoisting framemember for lifting and lowering the frame member, pump means forsupplying fluid under pressure to both of said cylinder and pistonmeans, conduit means connecting said pump means to said first mentionedcylinder means, conduit means connecting said pump means to said secondmentioned cylinder means, said second conduit means including a portionin common with said first mentioned conduit means, a fluid pressureoperated valve located between the common portion of said first andsecond mentioned conduit means and said second mentioned cylinder andpiston means for causing fluid to be passed first to the cylinder meansadapted to actuate said reciprocating tong and then to said cylindermeans adapted to lift said hoisting frame member, and valve means forcutting off the fiow of fluid under pressure from said pump means tosaid common conduit means, whereby a back pressure will be exerted uponthe piston of said tong actuating piston and cylinder means due to theweight of the load imposed on said second mentioned piston and cylindermeans.

4. In a hoisting apparatus of the type described, the combination of ahoisting frame member, a pair of clamping tongs dependingly carried bysaid frame member, one of said tongs being attached to said frame memberat a predetermined point thereon and the other of said clamping tongsbeing arranged for reciprocatory movement toward and away from saidfirst tong, guide means for said reciprocating tong, hydraulic cylinderand piston means for actuating said reciprocating tong, a secondhydraulic cylinder and piston means attached to the hoisting framemember for lifting and lowering the said frame member, pump means forsupplying fluid under pressure to both of said cylinder and pistonmeans, conduit means connecting said pump means to said first mentionedcylinder means, conduit means connecting said pump means to said secondmentioned cylinder means, said second conduit means including a portionin common with said first mentioned conduit means, a fluid pressureoperated valve located between the common portion of said first andsecond mentioned conduit means and said second mentioned cylinder andpiston means for causing fluid to be passed first to the cylinder meansadapted to actuate said reciprocating tong and then to said cylindermeans adapted to lift said hoisting frame member, and valve means forcutting off the flow of fluid under pressure from said pump means tosaid common conduit means, whereby a back pressure will be exerted uponthe piston of said tong actuating piston and cylinder means due to theload imposed upon said second piston and cylinder means.

5. In a hoisting apparatus of the type described, the combination of ahoisting frame member, a pair of clamping tongs dependingly carried bysaid frame member, one of said tongs being removably attached to saidframe member and the other of said clamping tongs being arranged forreciprocatory movement toward and away from said first tong after saidfirst mentioned tong has been attached to said frame member at apredetermined point thereon, guide means for said reciprocating tong,hydraulic cylinder and piston means for actuating said reciprocatingtong, a second hydraulic cylinder and piston means attached to thehoisting frame member for lifting and lowering the said frame member,pump means for supplying fluid under pressure to both of said cylinderand piston means, conduit means connecting said pump means to said firstmentioned cylinder means, conduit means connecting said pump means tosaid second mentioned cylinder means, said second conduit meansincluding a portion in common with said first conduit means, a

fluid pressure operated valve located between the common portion of saidfirst and second mentioned conduit means and said second mentionedcylinder and piston means for causing fluid under pressure to be passedfirst to the cylinder means adapted to actuate said reciproeating tongand then to said cylinder means adapted to lift said hoisting framemember, and valve means for cutting olf the flow of fluid under pressurefrom said pump means to said common conduit means, whereby a backpressure will be exerted upon the piston of said tong actuating pistonand cylinder means due to the load imposed upon said second hydraulicpiston and cylinder means.

References Cited in the file of this patent UNITED STATES PATENTS

